1. Field of the Invention
This invention relates to the marine industry and the ability to dry-dock large vessels in various ports, harbors, shipyards, and other marine facilities, specifically to a compact, self-leveling, and barge-like marine lift of efficient and expandable design that is capable of multi-directional off-loading of yachts, ships, and other marine vessels at ground level to dry-dock them. The present invention dry-docking lift apparatus can be portable and is designed to be taken to remote areas where haul-out facilities do not exist, and to also be used in any shore facility where space is limited. Further, the present invention has the advantage of self-containment for both local and remote use when it is fitted with a generator and/or means of propulsion (preferably in the form of add-on pods). In addition, since the costs of its manufacture and operation are lower than for many other structures and equipment used for marine vessel lifting purposes, and it does not require dedicated space, sharing the present invention between two or more shipyards is viable option for smaller facilities. The present invention design and construction allows for use of prime dockage at seawalls and piers, which is in contrast to other currently known units, such as the Synchrolift® elevator system, conventional railway systems, and mobile travel-lift units, which all have limited mobility at best and/or require a significant amount of dedicated space. The present invention also can be configured for multi-directional off-loading of a marine vessel at ground level via one or more of the following, a rail and cradle system, wheeled trailer-cradles, and an air-bearing or air-caster system, although not limited thereto. Since the present invention marine lift comprises independent platform sections joined together to meet any hull design, hull length, or water depth relating to large and small marine vessels, expansion or reduction of the present invention for differing uses is simple to accomplish and most qualified shipyards that would use the present invention will have the capability of adapting the platform sections and lift modules (also referred to herein as lift pods or lifting pods) for specific needs in a timely manner. Once the proper size of the present invention is formed, typically using two or more platform sections welded to one another but not limited thereto, and further when a sufficient number of lifting modules (or pods) are associated with the platform sections to successfully accomplish the raising and lowering of maximum anticipated loads during its use, the present invention can then be submerged simply by allowing the platform sections to fill with water. When the platform sections reach a depth sufficient to clear the bottom of a marine vessel hull that needs to be lifted to dock/seawall level, the marine vessel is moved into position over them, as well as shipyard-supplied cradle apparatus units positioned on the platform sections that will be used to maintain the marine vessel in a substantially upright orientation during the time it is out of the water. When the marine vessel in proper position, various conventional means of evacuating water from the platform sections can be used to raise them until the supported cradle apparatus comes into contact with the hull bottom. Then, once there is certainty that the marine vessel is adequately supported on the shipyard's cradle assembly, computerized lifting of the cradle assembly, the supported vessel, and the platform sections to dock/seawall level can begin via conventional jacking units located in the present invention's lifting pods. Marine vessels usable with the present invention dry-docking lift system are typically large and require an operating depth greater than the minimum depth needed for present invention use, therefore water depth issues are usually not a concern in present invention applications. However, as needed or desired, shallow water operations of the present invention can sometimes be facilitated by the optional presence of a recessed center section, which can be permanently formed (integrated) in the top surfaces of platform sections during their manufacture, or created as a result of removal of one or more reversibly detachable structural members. In addition, one or more platform sections of the present invention can be optionally configured for temporary containment of hazardous materials, such as harmful paint chippings, sand blasting debris, and other materials that result from work performed on marine vessels during their yearly dry-docking periods. Periodically, according to need or convenience, the hazardous materials would be withdrawn from their temporary storage location in the present invention and transported to facilities where they can be treated and recycled, or otherwise safely disposed of, thus allowing the shipyards in which it is used to become more environmentally safe. Further, unlike all other dry-docking units in current use, the ability of the present invention to be lowered to a harbor or shipyard seabed in the event of a severe storm, hurricane, or tidal surge provides the additional benefit of substantially reducing the possibility of damage or destruction to it and any marine vessel secured to it while it is submerged.
2. Description of the Related Art
Lifting a marine vessel out of the water for dry-dock maintenance and repairs has typically been expensive and required permanently-installed elevator systems, dedicated space, or both. Other disadvantages in using prior art dry-docking systems for marine vessel maintenance and repair operations include the inability to contain and/or safely dispose of environmentally hazardous materials that are generated, and difficulties involved in bringing a marine vessel to ground level, when needed. The graving dock is typically a narrow basin having a cradle that will ultimately support the marine vessel, which is floated into it through one end. Once the marine vessel is in proper position, a gate is closed and the water is pumped out, leaving the vessel supported on the cradle. Since the graving dock is substantially a hole in the ground, its disadvantages include the need for significant dedicated space and no mobility. Also, hazardous materials generated during maintenance and repair operations in a graving dock can easily find their way back into the environment when the gate is again opened to release the vessel. Another dry-dock configuration is the floating U-shaped dry dock. It has floodable buoyancy chambers that sink when valves are opened. After reaching an appropriate depth, a marine vessel can then be moved into it. Thereafter, when water is pumped out of the buoyancy chambers, the U-shaped dry dock floats and allows work to be conducted on the vessel's outer hull. The floating dry dock has a mobility advantage and can be used for ship maintenance or repair in remote locations. However, several significant disadvantages include instability and the difficulty in transferring a marine vessel to ground level, when needed. A sinker-lift platform is a third dry dock option. After its installation, it becomes part of a permanent structure extending out into the water and includes a vertically movable flat platform that can be lowered to allow positioning of a marine vessel upon a cradle, and then subsequently raised to ground level where the vessel and the cradle supporting it in concert can be off-loaded via a rail system. Multiple hydraulic motors located on both sides of the movable platform (at ground level) provide for its up and down vertical deployment, with the hydraulic motors being secured to immobile structure adjacent to the movable platform that guides it during its vessel raising and lowering operations. Disadvantages of sinker-lift platforms include a high installation cost, high maintenance costs, a large amount of dedicated space, non-portability, and potential interference with movement of other marine vessels in a shipyard or adjacent shipping lanes. A slipway can also be used to remove marine vessels from the water to a dry dock, which typically occurs most easily at high tide. Slipways comprise an inclined plane (ramp) that extends into the water. At high tide a marine vessel can be floated onto a cradle supported by the slipway, after which electric or electric-hydraulic winches haul the marine vessel out of the water. Although it is less expensive than other options, it has the disadvantages of requiring a significant amount of dedicated space, immobility, and possible infringement on water rights in narrow channels. In contrast, the present invention lift apparatus overcomes all of the disadvantages mentioned above for prior art marine lift systems. It can be portable, as well as adapted for self-contained transport and use with the addition of one or more generators and/or means of propulsion (preferably via the addition of add-on pods). It is designed to be taken to remote areas where haul-out facilities do not exist, and where space is limited in shore facilities. Add-on power supplies can provide power in remote locations where it would otherwise be unavailable for needed maintenance or repair work. The ability to share the present invention between shipyards is also a benefit for smaller facilities. In addition, the present invention has the ability to be configured for multi-directional off-loading by means of, but not limited to, a rail and cradle system, wheeled trailer-cradles, and an air-bearing or air-caster system. Further, independent platform sections allow the present invention to be configured according to need to meet any hull design, length and water depth. Once the proper size of the present invention is formed from assembled platform sections, and an appropriate number of lifting pods are associated with the platform sections, the present invention is simply submerged by allowing the platform sections to fill with water. Various conventional means of water evacuation can then be used to raise the platform sections until the shipyard-supplied cradle units supported upon them come into contact with the vessel's hull. Once the vessel is securely positioned on the cradle, the lift pods associated with the platform sections work in concert to raise them, the vessel, and the cradle units to ground level, while assuring substantially level orientation of the marine vessel. Another advantage of the present invention over all of the prior art is its ability to be lowered to a harbor or shipyard seabed in the event of a severe storm, hurricane, or tidal surge, whereby damage and destruction are at least significantly reduced, or eliminated. In addition, one or more of the present invention platform sections can optionally be configured for temporary containment of harmful paint chippings, sand blasting debris, and other materials that are removed from marine vessels during yearly dry-docking periods. No dry-docking lift apparatus is known that has the same structure or all of the advantages of the present invention.